The specification label from the inside of the cover of a Warrick liquid level control is visible here.

http://members.shaw.ca/peasthope/War...elControl.jpeg

The power supply and primary coil are 115 V. The secondary coils are 300 V.

This control switches a well pump which should start when the water level
reaches the upper probe and stop when the level drops below the lower probe.
Currently the pump fails to start reliably. The contacts were just cleaned.
The bar holding the contacts, which should carry current to the pump motor,
can be visibly displaced. Then there is a hum sound but the motor doesn't start. If the contacts are pushed open and then allowed to recoil shut, the motor starts.

Questions.

* Can anyone explain the TYPE notation? "TYPE 1C1D1" in this case.
A 1C1D0 appeared on eBay recently.

* Can anyone explain the FORM notation? "FORM 49" in this case.

* Listings of similar Warrick controls on eBay have secondary voltages ranging
from 15 V to 500 V. What are the criteria for choosing the secondary voltage?
My best guess is that lower voltages might work in salt water and higher
voltages might be necessary in distilled water. Is this topic documented?

* How is the hum sound generated? Presumeably it can exist when the motor is
running but be masked by the loud motor sound. Will a new control make the
same sound?

* With the relay assembled, the end of the contact holding bar is visible
but the contacts are not visible. Given that the contacts are clean, how
can the contact holder be displaced without delivering sufficient power
to run the motor?

* What is meant by "PILOT DUTY" on the label?

Thanks for replies, ... Peter E.